Color cinematography



T. A. MILLS.

COLOR CINEMATOGRAPHY.

APPLICATION FILED NOV:13. 1920.

Patented Feb. 28, 1922 UNITED STATESPATENT OFFICE.

THOMAS ALBERT MILLS, OF CLAIPHAM, LONDON, ENGLAND, ASSIGNOR TO ZOECHROMELIMITED, 01? LONDON, ENGLAND, A BRITISH COMPANY.

To all whom it may concern the following is a specification.

This invention relates to an improved method of producing cinematographfilms of the type in which each individual picture or element of thefilm is a complete color rendering of the subjects According to thisinvention there are produced uponthe negative film (by'the aid ofsuitable color screens) a set of images of full or normal size whichwill be referred to hereinafter as key images and interposed sets ofsmall sized color giving images, each preferably of half the lineardimensions of a key image. The small color giving images may be three"in number, corresponding to the usual triple division of colors, andthe key image taken without a color screen so as to give the black andwhite effect only. Or the key image may also be a color image, givingsay the blue in' the resulting positive film, either alone or, by adouble printing, the blue anda similar black and white ortrue key image,and only two small images may be produced. Each key image and its asso;

ciated small images are taken simultaneously through separate lensesand, as the lens for the large image has to have a correspondinglygreater focal length and if employed to give a direct imagewould form anobstruction for the small images, the increased focal length ispreferably provided for by a prism or other reflector, allowing all the,

lenses to lie in the'same plane. This displaces the key image from itscorresponding colorimages and therefore between the key' and colorimages of oneexposure. are interposed the key and color images of otherexposures.

the original negative the latter is moved at each operation through. adistance equal to a key image and the following small color images,

closlng up the key images on the positive film so thatthey arereproduced in succession without the interposition of the color images,these being afterwardsenlarged and superposed. The reproduction, if thekey image is to be in one of the colorsemployed,

COLOR CINEMATQGRAPHY.

k Specification of Letters Patent. Patented F b 28 1922. Applicationfiled November 13, 1920. Serial No. 423,961.

say blue, is suitably colored or dyed, but if the key image is black andwhite the usual process only is employed. Or the same large image may bereproduced twice, once as a black and white image and once in color. Thereproduced key film is then coated with a. sens1t1ve emulsion andone ofthe color sets of images is then enlarged to the key size and superposedupon the 'key images, the new positive 1mages being colored to therequired color, complementary. to that of the color screen employed forthe negative. The next set of color giving pictures is similarlysuperposed and, in the case of'the process employing black and white keyimages and three colors, the third set of color images is thensuperposed, with the result that the finished film is a complete colorrenderingof the subject and can be pro ected by the usual apparatus uponthe screen. The apparatus employed for producing the positive may be ofthe type descrlbed in the specification of British Patent No. 16353off-1913 (Middleton). It is to be understood that the term key image isused in a wide sense as the image which is 01']. lnally taken of fullsizeand thus serves as t e most important image in giving defini= t1onto the picture, but it is not necessarily an opaque or black and whiteimage in the positive picture.

In order that the said invention may be clearly understood and readilycarried into effect, the same will be more fully described withreference to the accompanying drawings, in which Figure 1 is a diagramillustrating theproduction of a negative having a set of key images andthree sets of color giving images; an

Figure 2 is a similar diagram illustrating the casein which the keyimage is also one -of the color giving images.

are the camera lenses, of which the larger lens D is of twice the focallength of the smaller lenses D. E is a prism reflector. The lenses arearranged as shown at the right of the figure, the small lenses formingan invertedtriangle belowthe large lens. The reflecting prism E isarranged so that placed in the same plane. The shutter mechanism andthecolor screens are not shown as they may be of ordinary type.

In Figure 2 the key pictures B are produced by the aid of a colorscreen, say red,

and instead of separating the images by a full picture width as inFigure 1 the separation is of half a picture width only, to accommodatea pair of small color images C taken through the two other, colorscreens of the set of three. placed symmetrically below the large lensD. Otherwise the arrangement is'as in Figure 1, and the prism reflectorE doubles the distance of the path from the lens D to the film.

In producing a positive from the negative film as shown in-either Figure1 or Figure 2 the key image is thrown-upon the positive film and thenegative film is moved for each exposure in the apparatus through thespace of two pictures or a picture and a half according to whether thearrangement of Figure 1 or Figure 2 is employed, the positive film beingmoved one picture space at a time. The positive film with the key imageson it is then developed and fixed and may be varnished beforesensitizing again. If

the key image is also a color one the positive film is colored to, say,blue. Or a black and white key image may be used and a second printingfrom the large images taken and colored.

The resensitized positive film is again exposed and' the enlarged imagesof one of the sets of small color images superposed upon the key images.The lens system employed for copying is arranged to give the requiredenlargement, while for the key pictures, the original and reproducedimages are of substantially equal size. The images B and O having beenrelatively displaced by the action of the reflector, the color imagessuperposed must be those separated by the intermediate images, asindicated by the dotted lines in the drawings, so that the color imagesshall be those taken by the same exposures as the key images on whichthey are superposed. The positive film is colored and resensitized againfor the second color set, the operations being repeated where a keyCpicture and three small pictures are employe as in Figure 1. The finalresult is a positive film fully colored and adapted to be projected bythe usual pro- The small lenses D are jecting apparatus. The three colorsystem has been taken as the basis of the method described andillustrated, but it is obvious that other color systems may be used.

Owing to the fact that the key images and the color images are takensimultaneously the original film should be moved more rapidly than isthe case with an ordinary film, since the space of two or of one and ahalf ordinary pictures has to be covered between each exposure, whilethe colored positive is moved at the normal speed for projection. Sincethe key image is of full size the projection on the screen gives aclearness of impression substantially as good as that of the ordinaryuncolored picture. To obtain this clearness it .is not essential thatthe color producing images should be so sharp,

so that the smaller scale, on which they are taken does not materiallyaffect the sharpness of the result and the great advantage is obtainedthat the color effect is given by an addition to the length of thenegative film of only 50 or 100 per cent according to the color'systememployed. The disturbing rainbow efi'ect produced when color-images aretaken successively is also entirely eliminated by the slmultaneousexposure of a complete set of images.

lVhat I claim and desire to secure by Letters Patent of the UnitedStates is 1. A method of making einematograph films which consists inproducing upon the negative film a set of full sized images with smallsized interposed images by simultaneous exposure of a. full sized imageand associated small sized images and producing from the said negativefilm a positive film by superposing in succession upon the said positivefilm the negative images, all brought to the said dimensions, andsuitably color ing the different superposed positive images, for thepurpose specified.

2. A method of making a negative film for the production of acoloredcinematograph positive film, which consists in producing a succession ofalternating key images of. full size and color giving images of smallsize, A

by a system of lenses and color screens, and providing for the greaterfocal length required for the full sized images by reflecting the beambetween the corresponding lens and the film.

3. A method of making colored cinematograph films which consists inproducing upon a negative film a succession of full sized key images andinterposed small sized color giving images whereby a plurality of colorgiving images occupy the length of film not greater than that of asingle key image, reproducing from the negative film a positive film bymoving the negative film in the posi- 'tive producing apparatus in stepsequal to a one image at a time, repeating the succession of reproducingoperations for each color employed and enlarging the small sized colorgiving images of the negative film to the same size as the key images onthe positive film, and, after a complete exposure of the positive film,coloring the positive images re-sensitizing the said film and producinga fresh set of images which are also colored repeating the operationsuntil the complete colored picture is obtained. c,

l. A negative vcine matogra-ph film for the production of a coloredpositive film, which negative film comprises a. succession of key imagesof full size along with a simultanea ously taken succession of colorgiving images of small size, whereby a plurality of color givingimages-occupies a length of film not greater than that of a single keyimage, for the purpose specified.

5. A negative cinematograph film for the production of a coloredpositive film, which negative film comprisesa' succession of key imagesof full size along with a simultaneously taken succession of colorgivingimages of half size, whereby a plurality of' color giving imagesoccupies a length of film not greater than that of a single key image.for the purpose specified.

6. A negative cinematograph film for the product-ion of a positivecolored film which negative film comprises a succession of full sizedkey images having interposed between each pair of full sized images aplurality of half sized color giving images obtained by simultaneousexposure with corresponding key images, whereby a plurality of colorgiving images occupies a length of film not greater than that of asingle key image, for the purpose specified.

7 A negative cinematograph film for the production of a positive coloredfilm, which negative film comprises a succession of full sized keyimages having interposed between each pair of full sized images a groupof three half size color giving images obtained by simultaneous exposurewith correspondnot greater than that of a single key image,

for the purpose. specified.

9. Apparatusfor the production of a negative film for use in obtainingacolored positive film, which apparatus comprises a. lens of focallength adapted to give cinematographic images of full size, a pluralityof lenses of shorter focal length coplanar with the first lens andadapted to give images of smaller size, and a reflector interposedbetween the film and the said first lens so as to provide for theincreased focal length, for the pur ose specified.

, 'FHOMAS ALBERT MILLS.

